Meat spoilage indicator



No Drawing. Filed iluly 29, 1958, Ser. No. 751,628

7 Claims. (Cl. 99-192) This invention relates to a novel indicator and,more particularly, it is concerned with an indicator for desig natingthe time that meat has been kept under conditions conducive to spoilage.

Storage of meats takes place under refrigerated conditions to preventmicrobial spoilage from occurring. However, it frequently happens thatmeat products in the course of handling are subjected to elevatedtemperatures at which rapid growth of food spoiling microorganisms takesplace. Casual inspection of the foodproduct is not sufiicient' to detectthe extent of spoilage during the inductive phase, and for this reasonproducts may appear sound to within an hour of the time that frankspoilage is manifest. It is apparent from the handling of meat productsthat there is lacking a simple inexpensive way of designating when theparticular food item has been subjected to adverse conditions for anundue period. Prior art workers have been investigating this problem forsome time but thus far no one has suggested a simple solution. Followingextensive investigation, it was found that a simple and economicsolution to the problem does exist.

Accordingly, itis an object of this invention to describe an indicatorwhich is" activatedby relationships of time and temperature which are inall respects similar to those conducive to microbial spoilage. Theindicator can be regarded as self-integrating with respect to time andtemperature. Response to time and temperature follows the same patternas the organisms responsible for rrri'c'robial spoilage.

Other objects and advantages of this invention will be come apparentfrom the following description and explanation'thereof. A

The microbial spoilage indicator of this invention coniprises apopulation of viable microorganisms, which" grow in approximately thesame temperature range as microorganisms associated with spoilage, anutrient or growth medium which may contain; apnea; and an indicatorwhich will" show when the microbial population has passed apredeterminedpoint-. Iii-the actiiie iiidicator all of the named com onents are in acommon aqueous system. While it is possible" to maintain the systemfrozen upto the time of use, it is more feasible to Ihdi am the waterapart from the microorganisms and nutrient until the time of use. In thepractice of this invention the microorganisms, nutrient, indicator, andwater are maintained separate and apart or enter contact with the meatproduct to avoid problerns of contamination. For this purpose thesematerials are kept'wifliin' a separate package which may take thefo'rin" of a traas arefitpiasae bag. The structural features of thepackage will be described in greater detail below. I

The microbial species employed is preferably one which is not capable-ofinducing food poisoning, ize. it is nonpath'ogfenic. Even though themicroorganism will not be in contactwith the meat product, it isadvisable to use a non-pathogenic microorganism because of thepossibility,

nited States Patent through inischanc'e, that such an organism willcontaininate the food product, The type of organism which can be usedfor this invention may vary considerably and include a large number ofclasses. The important feature in the selection of a microorganism isthat it must be capable of growthover the temperature range conducive tospoilage. -In this regard the microorganism may be any acid producingbacteria which undergoes rapid growth over a temperature range of about45' to about F. when in contact with a suitable growth medium ornutrient. a result of growth, the acid developed increases inconcentration to the point that it will attecr an acid-base indicatorand cause alcolo'r change therein. The change in the color of theindicator will serve to alert the handler of the meat prodiict that thedanger of frank spoilage is imminent. A microorganism which can be usedin this instance is the homoferrnentative lactic acid bacteria such as,for example, Lact o bzzcillus Ia'ctzs, Lactobacz'llus helv'eticus,Lqct'ob'acilfils ccidophilus, Lactobacilllls b'ifidus, Ldct'o'b'ac'illusbulgaricl'ls, Lact0bacillus case'i, Lactobacillils plantar'zmt, andothers. The microorganism can also be a mold with colored spores or onewhich undergoes ex} tensive mycelial growth. Bacteria or yeast growthwill cause turbidity, and an intensity scale calibrated to show theappropriate turbidity at excessive growth can be used as an indicator,

In general, th'equantity of microorganism relative to the nutrient canvary over awide range. In each specific case the population ofmicroorganisms per unit of nutrient is predetermined to produce a changewithin a temperature range which is expected to be experienced underactual service conditions. In the case of the homofermentative bacteria,it is convenient to use 500 to 20,000 viable cells per l ml. ofdissolved medium. I

The nutrient to be used is selected on the basis of being one which willpromote growth ofmicroorganisnis within the temperature range to beexperienced in the course of handling the meat product. The growthmedium must provide a nitrogen source suchas, for example, the peptoneswhich are the partially hydrolyzed natural proteins, e.g. bacto-peptone.Other examples of nitrogen supplying growth medium arehactodryptone,proteose peptone, bacto-tryptose,- neopeptone, bacto-casitone; bacto=protone, and bacto-casamino acids. Various other amino acids can also beused. The growth medium must also include a carbonsource for themicroorganisms. The carbon containing or supplying material can includethe monosaccharides, such as glucose, levulose, mannose or galactose;disaccharid'es, such as sucrose, lactose or maltose; thepolysaccharides, including starch, inulin, dextrin, glycogen, etc.; thealcohols, including glycerol, adonitol, mannitol, dulcitol, sorbitol',etc-.; the glucosides, including salacin, amygdalin, etc.; thenoncarbohydrate compounds, including inositol, etc. The quantity ofgrowth medium which is present with the microorganism is calculated toproduce a rapid growth within the specified temperature range so thatthe change'aifect'ed by reference to the indi-' cator will serve as adesignation to the handler of the product that the foodproduct hasundergone a more than safe limit of subjection to elevated temperature.It should be borne in mind that the quantity of nutrient is correlatedwith the population of microorganism and the type of indicator to beused.

The indicator is selected on the basis of the type of microorganism andnutrient which are used in the system. Where the microorganism is anacid producing bacteria, an acid-base indicator is employed. In thisconnection the indicator is, for example, bronioplieriol blue,b'romochlorophenol blue, bromocresol' green, chlo rocresol green, methylred, chlorophenol red, hrom'ophenol red, bromocresol purple, bromothymolblue and related with the type of microorganism used and the 8 nutrientto be supplied therefor. When yeast is used as 1.0%- the microorganism,the indicator is a turbidity scale which Example IV phenol red. Theindicator must not exert a significant inhibitory effect on the activityof the microbial culture. Itwill be noted from the type of indicatorsenumerated Percentage Name of Material above that the color change willtake place at various pH levels. This means that the indicator must becor- 5 0.50%

shows the extent of colony growth representing the point at which thetemperature history of the food product has been undesirable from thestandpoint of spoilage. The indicator system of this invention ispreferably Active dry yeast. Yeast extract. t ol. Sucrose.

Water.

(In this case, gas production as manifestby swelling of the packageindicatesdanger of spoilage.)

maintained in the anhydrous state until the start of. the Example Vperiod it is to monitor. Generally the indicator system is not activateduntil the meat is packaged or removed 5 Percentage Name otMaterlal frominventory. The indicatorisystem is activated by bringing all components(microorganism, nutrient and indicator) into a common aqueous solution.In order to assure uniformity of activity it is desirable to utilizelyophilized or freeze dried cultures. The growth medium or utrient islikewise maintained in a dried state. In this way the indicator canbe'put into "operation at the convenience of the handler in' order thathe can con- Sucrose.

Water.

Potassium nitrate.

Potassium monohydrogen phosphate. Magnesium sulfate.

Sodium chloride.

Ferrous sulfate.

Dry bread inoculated with spores trom Penicillium (mold species).

trol zero time in respect to the history of the meat product. Theindicator system is placed in a suitable pack- (At the danger point,this indicator becomes a green age. The package can be a sealed envelopedivided into two compartments which are separated by a rupturablemembrane. The material making up the package is either translucent ortransparent so that the color change mat of mold.)

Having thus provided a description of my invention along with specificexamples thereof, it should be understood that no undue restrictions orlimitations are can be witnessed without difiiculty. Various plastic mato be imposed by reason thereof but that the present terials lendthemselves to use for this purpose such as, for example, polyethylene,Mylar, Kel-F, Teflon, Lucite, etc. In any case, the bag or package ispreferably flexible so that the separated membrane can be easily rup- Iclaim:

invention is defined by the appended claims.

1. A temperature indicator comprising a package containing two separatecompartments, one compartment tured by the operator and put theindicator into operaontaining a lyophilized microorganism capable oftion. As might be expected, the package or envelope is' waterproof sothat the only source of water is that contained within the separatecompartment of the'packcelcrated growth with increasing temperature, adried nutrient for the microorganism and "an indicator for showing thatthe growth of microorganism is greater than a desired limit, the secondcompartment containing In order to better understand the presentinvention, 40 watmd h two compartments b i separated by a membrane whichis capable of'being broken manually.

2. A temperature indicator comprising a package containing twocompartments which are separated by a rup-turable membrane capable ofbeing broken manually,

Example I one compartment containing a lyophilized acid producingmicroorganism, a dried nutrient for the organism and an acid-baseindicator for showing that the growth of micro- Pe centa e Name of Matelal r g r organism is greater than the desired hunt, and the othercompartment contains water. L o hilized Ped ococcus carer s as. Ppibime. 1 Z I 3. The temperature indicator of claim 2 wherem the ggii gmicroorganism is a lactic acid producing bacteria. Bromocresol purple.4. A temperature indicator comprising a package containing two separatecompartments, one compartment Example Ii Percentage Name of Material%yophilized Pediococcus cerevzsiae. a able of being broken manually.

ryp one.

Dextrose 5. A temperature indicator comprising a package conggg ftaining two separate compartments, one compartment containing an acidproducing microorganism capable of accelerated growth with increasingtemperature, a dried Example 111 nutrient for the microorganism and anacid base indicator for showing that the growth of microorganism is Nameof Material 7 7o Lyophilized Pediococcus ccrcvisiae. manually Yeastextract.

Dextrose. Potassium monohydrogen phosphate. Bromothymol blue.

greater than a desired limit, the second compartment containing waterand the two compartments being separated by a membrane which is capableof being broken 6. A temperature indicator comprising a packagecontaining two separate compartments, a first, compartment containing alyophilized culture of Pediococcus cerevisiae Water. i capable ofaccelerated growth with increasing tempera- I 7 ture, a growth mediumconsisting of peptone, yeast extract and dextrose and an indicatorselected from the group consisting of bromocresol purple andchlorophenol red for showing that the growth of lyophilized culture isgreater than a desired limit, the contents of said first compartmentbeing essentially anhydrous, the second compartment containing water andthe two compartments being separated by a membrane which is capable ofbeing broken manually.

7. A meat spoilage indicator comprising a package containing twoseparate compartments, a first compartment containing a predeterminedamount of an organism capable of accelerated growth with increasingtemperature, a correlated amount of nutrient for said organism to bringabout accelerated growth of said organism at temperatures of meatspoilage, and an indicator for designating visually the condition ofsaid accelerated growth, the contents of said first compartment 'beingessentially anhydrous, the second compartment containing water and thetwo compartments being separated by a membrane which is capable of beingbroken manually.

References Cited in the file of this patent UNITED STATES PATENTS2,485,566 Clark Oct. 25, 1949

1. A TEMPERATURE INDICATOR COMPRISING A PACKAGE CONTAINING TWO SEPARATECOMPARTMENT, ONE COMPARTMENT CONTAINING A LYOPHILIZED MICROORGANISMCAPABLE OF ACCELERATED GROWTH WITH INCREASING TEMPERATURE, A DRIEDNUTRIENT FOR THE MICROORGANISM AND AN INDICATOR FOR SHOWING THAT THEGROWTH OF MICROORGANISM IS GREATER THAN A DESIRED LIMIT, THE SECONDCOMPARTMENT CONTAINING WATER AND THE TWO COMPARTMENTS BEING SEPARATED BYA MEMBRANE WHICH IS CAPABLE OF BEING BROKEN MANUALLY.